The proposed project is an epidemiological study of the mortality of drug abusers; it fills a serious gap in our knowledge of drug abuse, and will provide basic data for the drug field comparable to that available for alcoholism. It is a prospective study of identified substance abusers observed from 6 1/2 to 13 years, (average = 8 1/2). It is thus not a study of drug abuse deaths, but of deaths among drug abusers, regardless of cause of death. The study has three parts: I. Data on the mortality of 6,900 substance abusers will be gotten from death records confirmed and expanded by other records and interviews with survivors; 5,600 cases will be drug addicts and 1,300 alcoholics (300 of whom also abused drugs). There will be an estimated 59,000 person years at risk; over 600 decedents are anticipated. These data will yield both total and cause-specific death rates, changes in mortality experience over the years of observation, and comparisons among subgroups of subjects as well as between them and general population data. II. Predictors of excess mortality will be investigated by the case-control method. For each decedent, a comparison case will be drawn, matched for age, sex, race, type of substance abuse, and date of intake. The two groups will be compared with regard to extensive medical, substance abuse, demographic and personal data obtained on admission, to identify predictors of premature death among drug abusers. III. Does the substance abuser who achieves rehabilitation thereby increase his or her life expectancy? Some evidence suggests this, but it has not been well tested. Fortunately, the applicant has conducted four large NIDA funded treatment outcome studies, including 2,400 cases from this study. Data from these cases will compare post-treatment outcome with later mortality. The project is a significant study of the public health consequences of drug abuse. Its value is greatly enhanced by the fact that at intake thorough medical history and examination were obtained. We thus hope to learn how to identify drug addicts who are at particularly high risk for premature death so that appropriate intervention can be made.